Biologists and chemists desire a technique for separating and/or sorting substances, molecule by molecule. For example, biologists and chemists would like to be able to determine which type of molecule(s) remains after a test reaction. In addition, biologists and chemists seek improved methods for processing molecules in a sample batch. It will be recognized that molecular dimensions are on the order of nanometers, thus, separating and/or sorting of molecules has been difficult to achieve. In addition, process controls require the use of proportional flow control valves.
In a conventional filtering process, a batch of material is presented to a filter having interleaved elements (e.g., many layers of extremely fine filter cloth). The unfiltered sample material passes through each of the filter layers so that a filtered sample material is provided at an output of the filter. With this filtering process, large amounts of the sample material are typically lost in the filter, since conventional filters enable only one molecule size to be sorted, and molecules with larger sizes are lost in the filter material. Thus, undesirably, filtering a batch of sample material using a conventional filtering process requires the use and loss of a large quantity of the sample material.
Biological samples, such as DNA, tend to be very expensive, on the order of tens of thousands of dollars per gram. Loss of sample material can be very expensive. Therefore, conventional filters have not provided an efficient mechanism for separating and/or sorting molecules of biological samples.
It would, therefore, be desirable to provide a mechanism with which particles, such as molecules, suspended in a fluid can be separated and/or sorted, while reducing the amount of sample material lost in the process. It would be further desirable to provide a mechanism with which the particles suspended in the fluid can be selectably separated and/or sorted, such that the same mechanism can be used to select and/or sort suspended particles having a variety of sizes. It would still furthermore be desirable to proportionally control the flow rate of a fluid to a very fine degree.